1. Industrial Field of the Invention
The present invention relates to rubber compounds that make reclaimed use of vulcanized scrap rubber, methods for manufacturing such rubber compounds and reclaiming agents used in such methods.
2. Prior Art
Conventionally known methods of reclaiming vulcanized scrap rubber include the open steam method (pan method), the digestor method, the mechanical method and the UHF heater devulcanization method (U.S. Pat. No. 4,104, 205), which makes use of microwave energy. However, these methods require large-scale desulfurization equipment such as the devulcanizer, digestor, reclaimator, super mixer and UHF heating equipment. Also, since treatments are performed in each of these methods under high temperature or high pressure conditions, large quantities of energy are required and the working environments are characterized by irritating odors and high temperatures. Thus, there is much demand for improvement. Furthermore, since these methods require that the ratio of fibers and other foreign objects mixed in the scrap rubber be reduced to 1% or less, multi-step processes had to be provided for the removal of fibers and other foreign objects prior to the devulcanization process.
With regards to methods of ordinary temperature reclamation of scrap rubber, a study by Yamashita and others at Kyoto Industrial Textiles University is known (Journal of the Rubber Society of Japan, Vol. 49, No. 12, pp. 908-911, 1976). However, since a tributylamine--iron (I) chloride chemical is used in this method, it carries the problem of irritating odors and since a long period of time (20-50 hours) is required for the reclamation, there are difficulties in putting this method to practical use.